During opencast coal mining, it is necessary to pump and discharge a great plenty of water to ensure a smooth production. Currently, coal mine water pumping and discharge are mainly carried out by water discharge, thus seriously wasting water resource. In addition, the underground water reservoir for storing opencast coal mine water as pumped and discharged is different from the traditional ones. It not only needs an underground space constructed for water storage, but also needs a function of filtering and purification, thus enabling filtering and purification of a polluted water source produced during coal mining.
However, a prior underground water reservoir can not meet a requirement for filtering and purification of the polluted water source, so a water source polluted during coal mining is directly discharged or stored without purification processing, thus seriously polluting the environment.